In recent years, fine bubbles (ultrafine bubbles or micro bubbles) which are formed in water and have a diameter of, for example, several tens nm to several hundreds nm have gained attention. For example, Patent Literature 1 discloses a technique of using fine bubble water for washing in which a fine bubble generation device (UFB unit) is provided in a water supply path in a washing machine to generate numerous fine bubbles, and fine bubble water including the fine bubbles is used for washing. Using such fine bubble water enables to enhance dispersibility of detergent and permeability of detergent into clothes, thus achieving excellent cleaning action.